The season-altering and potentially season-ending injury Michael Crabtree suffered Tuesday leaves the San Francisco 49ers with question marks at wide receiver.Anquan Boldin becomes the most productive healthy receiver available to the team. Mario Manningham and Kyle Williams are coming off injury-shortened seasons.2012 Production for Current 49ers WRsMarlon Moore, signed from the Miami Dolphins, is the only other wideout on the roster with a reception to his credit last season.